1. Field of the Invention
The present invention relates generally to an agricultural implement, including a floating header. More particularly, the present invention relates to an improved suspension system for agricultural implements having one or more floating headers wherein the suspension hydraulic cylinders are also used to lift the header for transport.
2. Background Art
A three-point mounted mower with a suspension system is disclosed in U.S. patent application Ser. No. 5,417,042. Disclosed in this application is an example of a mower suspension system with separate elements having a first and a second chamber and separate fluid inlets. These pairs are intended for different functions. One pair is used to lift to a transport position while the other pair is used to transfer oil during operation to suspend the header.
Another example of a three-point mounted mower is disclosed in U.S. Pat. No. 6,085,501. This patent describes a machine where the frame is not lifted to raise the header to a transport position, but where there are effectively two separate cylinders, one to lift into transport, another to suspend the header. The patent describes separate hydraulic rams.
An example of a typical suspension for a trailed mower or mower conditioner is disclosed in U.S. patent application Ser. No. 6,055,800, wherein a cylinder lifts the frame and header to a transport position, while a spring provides a lift force to suspend the header in working position.
The multiplicity of components for lifting and suspending a floating header on a fixed-frame agricultural implement increases complexity, cost, while decreasing reliability.
There is, therefore, a need for a method and apparatus for both lifting and providing suspension for a floating header on a fixed-frame agricultural implement such as a mower.